(1) Field of the Invention
This invention relates to formaldehyde-free finishing agents for increasing wrinkle resistance in textiles.
(2) Description of the Prior Art
Textiles composed of cellulose, such as cotton or rayon and their mixtures with synthetic fibers, are often finished with chemical agents to impart the ability to resist wrinkling and musing in use and during laundering. These agents also reduce fabric shrinkage due to laundering. These finishing agents are compounds that contain two or more groups capable of reaction with cellulose. During the finishing operation, the agent reacts with two polymeric cellulose molecules to form crosslinks or bridges between the cellulose chains.
The finishing agents now in common use are prepared from the reaction of formaldehyde and amides to form methylol compounds, or hydroxymethylamides. Typical examples are 1,3-dimethylolurea, 1,3-dimethylol-2-imidazolidinone, and 4,5-dihydroxy-1,3-dimethylol-2-imidazolidinone. These agents are quite effective for the intended purpose. However, the agents and their reaction products on the finished fabric often decompose or hydrolyze slowly releasing formaldehyde. This is a decided drawback because even small amounts of formaldehyde are irritating and may be hazardous.
To avoid formaldehyde release, agents have been sought that are not made from formaldehyde and do not release formaldehyde on decomposition. Such agents have been made from the reaction of glyoxal and a urea to make 4,5-dihydroxy-2-imidazolidinone and its derivatives as described in U.S. Pat. Nos. 3,112,156 and 3,260,565. In reaction with cellulose, these compounds are difunctional, the minimum functionality required to produce crosslinks. As finishing agents, these compounds are not as effective as the compounds made from formaldehyde. They can not impart the degree of wrinkle resistance imparted by the compounds made from formaldehyde.
Compounds containing more than two reactive groups have been made from glyoxal and monoureas. An example is 1,2-bis(4,5-dihydroxy-2-oxoimidazolidin-1-yl)-1,2-dihydroxyethane prepared by A. H. Dinwoodie, G. Fort, and J. M. C. Thompson, Journal of the Chemical Society C1967, (23), 2565-2568. These compounds should be more reactive because of their greater functionality. However, these compounds also contain other hydroxyl groups that interfere in their reaction with cellulose. They are, therefore, relatively ineffective as finishing agents.